Scape Terrain Editor
Scape is a terrain editor which can be used to create and sculpture virtual terrains. This terrains can be exported into heightmaps and can be reused in 3d applications such as games.
This was originally a fork of Giliam de Carpentier's Scape terrain editor which has been ported to Qt (from wxWidgets) and updated to work with the latest OGRE version.
It was also extended by some features that were not available in the original.
This editor is pretty usable but it could still handle some improvements.
There are some guides available in this repository which can help you with building and using Scape.
This editor has been tested on Windows and Linux.